U.S. patent application number 12/420165 was filed with the patent office on 2010-03-18 for device for feeding combustion air to an engine of an aircraft.
This patent application is currently assigned to Eurocopter Deutschland GmbH. Invention is credited to Serge Macchi, Bernd Osswald.
Application Number | 20100065139 12/420165 |
Document ID | / |
Family ID | 41173244 |
Filed Date | 2010-03-18 |
United States Patent
Application |
20100065139 |
Kind Code |
A1 |
Osswald; Bernd ; et
al. |
March 18, 2010 |
DEVICE FOR FEEDING COMBUSTION AIR TO AN ENGINE OF AN AIRCRAFT
Abstract
A device for feeding combustion air to an engine disposed in an
interior of an aircraft is comprised of an air inlet duct extending
between an exterior surface of the aircraft and the engine, wherein
the air inlet duct extends from air inlets disposed in a first
region of the exterior surface; at least one further air inlet duct
extending between a second region of the exterior surface and the
engine, so as to provide a two-way airstream supply; and a control
device configured to switch the air supply to the engine to the at
least one further air inlet duct when a blockage occurs in the air
inlets.
Inventors: |
Osswald; Bernd; (Mertingen,
DE) ; Macchi; Serge; (Salon De Provence, FR) |
Correspondence
Address: |
DARBY & DARBY P.C.
P.O. BOX 770, Church Street Station
New York
NY
10008-0770
US
|
Assignee: |
Eurocopter Deutschland GmbH
Donauwoerth
DE
|
Family ID: |
41173244 |
Appl. No.: |
12/420165 |
Filed: |
April 8, 2009 |
Current U.S.
Class: |
137/625.44 |
Current CPC
Class: |
B64C 27/04 20130101;
B64D 33/02 20130101; F05D 2220/329 20130101; Y10T 137/86847
20150401; F02C 7/052 20130101 |
Class at
Publication: |
137/625.44 |
International
Class: |
F16K 11/052 20060101
F16K011/052 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 8, 2008 |
DE |
10 2008 017 962.0 |
Claims
1. A device for feeding combustion air to an engine disposed in an
interior of an aircraft comprising: an air inlet duct extending
between an exterior surface of the aircraft and the engine, wherein
the air inlet duct extends from air inlets disposed in a first
region of the exterior surface; at least one further air inlet duct
extending between a second region of the exterior surface and the
engine, so as to provide a two-way airstream supply; and a control
device configured to switch the air supply to the engine to the at
least one further air inlet duct when a blockage occurs in the air
inlets.
2. The device as recited in claim 1, further comprising at least
one inflow flap corresponding to the at least one air inlet duct,
and wherein the control device is configured to open the at least
one inflow flap.
3. The device as recited in claim 2, wherein the at least one
inflow flap is movable along a rail guide using a hydraulic
cylinder or an electric linear drive between an open position and a
closed position.
4. The device as recited in claim 2, wherein the at least one
inflow flap is disposed so as to be rotatable on a hinge.
5. The device as recited in claim 1, further comprising a pressure
sensor connected to the control device configured to detect the
blockage of the air inlets, and wherein the control device contains
a defined pressure threshold value.
6. The device as recited in claim 1, wherein the at least one
further air inlet duct includes two further air inlet ducts on
opposite longitudinal sides of the exterior surface, the
longitudinal sides extending between fore and aft of the aircraft,
each further inlet duct having an end inlet-cover filter
element.
7. The device as recited in claim 1, wherein the aircraft includes
a second engine, and wherein the at least one further air inlet
duct is a single further air inlet duct for each engine having an
associated end inlet-cover filter element, and wherein the second
region is at the top of the exterior surface of the aircraft.
8. The device as recited in claim 7, further comprising a firewall
affixed to the engine and wherein the at least one air inlet duct
for each engine is detachably attached to the firewall.
9. The device as recited in claim 7, wherein the at least one air
inlet duct is comprised of a high-temperature-resistant BMI
(bismaleimide) material.
10. The device as recited in claim 7, wherein the inlet-cover
filter element includes a closed attachment frame enclosing a flat
filter body, the flat filter body including a protective grill at
least externally.
11. The device as recited in claim 1, wherein the at least one
further air inlet duct includes at least one further inlet-cover
filter element.
12. The device as recited in claim 1, wherein each air inlet
includes an additional inlet-cover filter element.
13. A helicopter comprising: a rotor-driving engine; and a device
for feeding combustion air to the engine, the device including an
air inlet duct extending between an exterior surface of the
aircraft and the engine, wherein the air inlet duct extends from
air inlets disposed in a first region of the exterior surface; at
least one further air inlet duct extending between a second region
of the exterior surface and the engine, so as to provide a two-way
airstream supply; and a control device configured to switch the air
supply to the engine to the at least one further air inlet duct
when a blockage occurs in the air inlets.
Description
[0001] Priority is claimed to German Patent Application No. DE 10
2008 017 962.0, filed on Apr. 8, 2008, the entire disclosure of
which is incorporated by reference herein.
[0002] The present invention relates to a device for feeding
combustion air to an engine of an aircraft, comprising a primary
air-inlet duct, which extends between the exterior surface of the
aircraft and an air inlet of the engine that is arranged in the
interior and comprises an inlet-cover filter element in the region
of the exterior surface.
[0003] The field of application of the present invention primarily
extends to aircraft in the form of helicopters. In order to drive
the rotor, an engine is housed within the cell of a helicopter. The
engine is designed as an internal combustion engine that receives
the air that is required for combustion from the environment. For
this purpose a device according to the invention for feeding
combustion air is arranged between the engine and an air inlet of
the cell of the helicopter.
BACKGROUND
[0004] From WO 2007/090011 A2 a generic device is known. It
comprises an air inlet duct that extends between the exterior
surface of the helicopter and the engine, which is arranged on the
interior, which air inlet duct comprises an inlet-cover filter
element that is flush with the exterior surface of the helicopter.
In this arrangement the inlet-cover filter element follows the
contour of the exterior surface and comprises an exchangeable flat
filter body that is held by a closed attachment frame made of
metal, and that on both sides comprises a protective grille. The
inlet-cover filter element filters the air from the environment,
which air is ingested by the engine, in order to stop foreign
objects and dirt particles from entering the engine by way of the
air inlet duct. After a certain period of time the filter body of
the inlet-cover filter element is usually blocked and requires
cleaning. Thereafter it can again be placed into the attachment
frame. The attachment frame is used to ensure the desired shape of
the filter body and thus its function even at high rates of flow of
air from the environment.
[0005] In the implementation of an inlet-cover filter element for
the engines to be protected, for reasons associated with safety, it
must always be ensured that the icing behaviour on the filter
bodies and on the air inlet duct is kept within permissible limits.
The installation of an inlet-cover filter element that is used to
prevent premature engine wear as a result of erosion is always a
far-reaching intervention in the conception of the air inlet duct.
As a rule, only a single air inlet duct will be available for
feeding combustion air to an engine. In such a single engine inlet,
performance loss due to the pressure loss resulting from the filter
body that is installed upstream will practically be unavoidable.
Dangerous hazard conditions arise in particular when icing of the
filter body results in total air impermeability.
[0006] In U.S. Pat. No. 4,190,217 a device for the supply of
combustion air to an engine of an aircraft is stated, in which
device the above-mentioned problem is solved in that in the region
of the inlet-cover filter element an additional inflow flap is
provided. If the inlet-cover filter element is clogged, then this
inflow flap opens in order to lead a replacement airstream, which
will then, however, not be filtered, to the engine. This emergency
measure is associated with a disadvantage in that engine wear
cannot be avoided. If the above-mentioned emergency situation
arises, and if at the same time the air from the environment is
severely contaminated with coarse dirt particles, emergency
operation can directly lead to situations in which the engine
sustains considerable damage.
[0007] From prior art it is also known, instead of providing an
inflow flap that is arranged beside the inlet filter element, to
design the filter element itself so that it is tiltable so that the
gap forming between said filter element and the exterior surface of
the aircraft makes possible an emergency supply of non-filtered
combustion air. Most of the time this results in severe inlet
losses to the engine. Since it must always be ensured that the
available performance exceeds the maximum weight of the helicopter,
this inlet loss is a limiting factor.
SUMMARY OF THE INVENTION
[0008] An aspect of the present invention is to provide an
efficient device for feeding combustion air to an engine of an
aircraft with simple technical means ensuring minimum engine wear
but nevertheless providing an adequate air supply in emergency
operation.
[0009] The invention includes the technical teaching according to
which for the purpose of implementing a two-way airstream concept
at least one further air inlet duct is provided which leads from
another point on the exterior surface to the region of the air
inlet, the air inlet duct comprising an associated further
inlet-cover filter element, wherein the supply to the engine in the
case of a blockage in the primary air-inlet duct switches over to
the further air inlet duct according to a control device.
[0010] The solution according to the invention provides an
advantage in particular in that by way of the further air inlet
duct, in other words the reserve air inlet duct, which can comprise
an inlet-cover filter element in the same manner as the primary
air-inlet duct, in the case of an emergency an adequate quantity of
combustion air can reach the engine. This measure improves
operational safety of the aircraft because the performance of an
engine is ensured in every case. In order to implement the measure
according to the invention, it is merely necessary to affix a
further inlet-cover filter element at a suitable position on the
exterior surface of the cell of the aircraft, and to connect it to
the air inlet of the engine by way of an air inlet duct.
[0011] According to a measure that improves the invention, it is
proposed that the control device for switching over the air supply
opens an associated inflow flap by way of the at least one further
air inlet duct. In this arrangement the inflow flap can be arranged
in the region between the air inlet duct and the air inlet of the
engine. On the one hand it is imaginable to design the control
device for switching over as an automatic electronic control device
so that once a sensor has detected a blockage in an inlet-cover
filter element said control device automatically opens the inflow
flap for the further air inlet duct. On the other hand it is also
imaginable to merely signal the blockage situation in the cockpit,
so that the pilot can open the inflow flap of the further air inlet
duct by manual intervention.
[0012] The inflow flap can be designed according to the following
alternative embodiments:
[0013] It is proposed that the inflow flap be moved, along a rail
guide by means of a hydraulic cylinder or an electric linear drive,
between the open position and the closed position in the manner of
a flat slide valve. This design has been shown to be particularly
robust and can be implemented with simple technical means. As an
alternative to this it is proposed that the inflow flap be affixed
so that it is rotatable on a hinge. This design is particularly
suitable where the design space is limited. However, the hingeable
inflow flap should be arranged so that it opens in the direction of
flow of the combustion air in order to support the opening by way
of the suction effect of the engine.
[0014] According to a further measure that improves the invention,
it is proposed that a blockage of the primary air-inlet duct is
determined by means of a pressure sensor that is placed in that
position and that is connected to an electronic control device,
with the pressure sensor able to be arranged in the region of the
air inlet of the engine. Any increasing clogging of the inlet-cover
filter element, up to a blockage of the air stream, results in a
drop in pressure in the downstream air inlet duct, and the drop in
pressure can be determined by the pressure sensor. This value can
be compared within the electronic control device, with a defined
pressure threshold value that has been deposited in said control
device. Once the predetermined pressure threshold value has been
reached, signalling takes place to the effect that the further air
inlet duct is to be connected. In the automatic variant, the
subsequent connection takes place automatically. Instead of
providing a pressure sensor that is designed in the manner of an
absolute pressure sensor, it is also imaginable to use a
differential pressure sensor for the above-mentioned purpose, where
differential pressure sensor monitors the pressure differential
between the air inlet duct and the environment, and once a defined
pressure differential has been reached signals and/or initiates the
switch-over according to the invention. Manual and automatic
connection of the second air duct can also be carried out in a
combinable manner, depending on the operating state. If prior to
the complete clogging of the inlet-cover filter element the second
inlet duct is connected in addition, then the air flowing around
the aircraft ensures that there is negative pressure, and the air
supply via the alternative route ensures that there is positive
pressure at the inlet-cover filter element, which causes an
automatic restoring effect as a result of a change in the direction
of the air.
[0015] As far as the air-inlet duct design is concerned,
alternative embodiments are also imaginable:
[0016] As a preferred embodiment it is proposed that two further
air inlet ducts, each with associated end inlet-cover filter
elements, are arranged opposite each other on both longitudinal
sides of the exterior surface, where the longitudinal sides extend
between fore and aft. This design is particularly suitable in the
case of smaller helicopters because the lateral surfaces of the
engine deck usually provide sufficient space to arrange the
additional inlet-cover filter elements. Furthermore, this design
and arrangement allows quite short air inlet ducts to the engine.
In this design the air inlet ducts can be detachably attached to
the firewall, which, for safety reasons, is advantageously affixed
directly to the engine, which minimises installation
expenditure.
[0017] According to yet another embodiment, which is suitable in
particular for large helicopters, a single further air inlet duct
for each engine with an associated end inlet-cover filter element
is arranged at the top of the exterior surface of the helicopter.
In particular the region of the exterior surface that is directly
adjacent to the exiting main rotor shaft is suitable as a point of
exit of this further individual air inlet duct.
[0018] Of course, it is also possible to combine the two previously
mentioned preferred embodiments.
[0019] Since the air inlet duct usually extends adjacent to the
engine, it is proposed that said air inlet duct be produced from a
high-temperature-resistant BMI-(bismaleimide) material or material
mixture with a component thereof and the addition of further
materials, in particular carbon fibres. Apart from its high
temperature resistance, this material also features a low specific
weight and can be made to adapt in a simple manner to the different
shapes of air inlet ducts.
[0020] Of course, it continues to be possible to combine the
measure according to the invention of a two-way airsteam supply
with conventional bypass flaps for the supply of non-filtered
bypass air. However, such a bypass flap should only be used in an
absolute emergency so as to avoid, if at all possible, any
ingestion of non-filtered combustion air in the engine.
[0021] Further advantages, characteristics and application options
of the present invention are stated in the following description in
conjunction with the exemplary embodiments shown in the
drawings.
[0022] Below, the invention is described in more detail with
reference to the exemplary embodiments shown in the drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In the description, in the patent claims, in the abstract
and in the drawing the terms and associated reference characters
used in the list of reference characters below are used.
[0024] The drawing shows the following:
[0025] FIG. 1 a top view of the cell of a helicopter with two-way
airstream guidance with the use of two air inlet ducts, in the
illustration shown in their closed state,
[0026] FIG. 2 a top view of the cell of a helicopter with two-way
airstream guidance with the use of two air inlet ducts, in the
illustration shown in their open state; and
[0027] FIG. 3 a partial lateral section view of a detail of a
helicopter in the region of the engine with two-way airstream
guidance according to a further embodiment.
DETAILED DESCRIPTION
[0028] In the following description and in the figures, for the
purpose of avoiding repetition, the same reference characters are
used for identical components, provided no further differentiation
is required or sensible.
[0029] According to FIG. 1 in the upper part of a cell 1 of a
helicopter there is a left-hand air inlet 2a and a right-hand air
inlet 2b arranged adjacent to it, with both air inlets being used
in normal operation. From the environment, combustion air flows to
an engine 3a and an engine 3b arranged in the interior of the cell
1. A primary air-inlet duct 4, which starts at the air inlets 2a
and 2b, passes through a main gearbox (not shown in detail in the
illustration) of the helicopter.
[0030] In order to implement a two-way airstream concept, apart
from the air inlet duct 4 that leads into a central duct 7 near the
engine, two further air inlet ducts 8a and 8b each with associated
inlet-cover filter elements 9a and 9b are arranged opposite each
other on both longitudinal sides of the helicopter, which
longitudinal sides extend between fore and aft of the cell 1. The
two air inlet ducts 8a and 8b comprise a high-temperature resistant
BMI material, and at their ends opposite the respective inlet-cover
filter element 9a or 9b they comprise inflow flaps 10a or 10b.
[0031] During normal operation the two inflow flaps 10a and 10b
remain in the closed position as shown in the illustration.
[0032] According to FIG. 2, the two inflow flaps 10a and 10b are in
their open position, in which, by way of a substitute, combustion
air is fed (see arrows) by way of the central duct 7 to the engine
3a, 3b. In this exemplary embodiment the two inflow flaps 10a and
10b are moved along a rail guide by means of hydraulic cylinders
(not shown) between the open position and the closed position.
[0033] Starting from the air inlet 2a and 2b the combustion air,
guided by the air inlet duct 4, flows past a main gearbox 12 of the
helicopter and through the central duct 7 to the engine 3a and
3b.
[0034] In the case of an emergency, for example a blockage of the
air inlets 2a, 2b, the two flaps 10a and 10b open so that the
combustion air required by the engine 3a, 3b can be fed by way of
the air inlet ducts 8a and 8b.
[0035] The further exemplary embodiment shown in FIG. 3 only shows
a single further air inlet duct 8' for each engine, with an
associated end inlet-cover filter element 9' on the exterior
surface 5 of the cell 1 (only partially shown in the illustration),
In this arrangement the air inlet duct 8' is detachably attached to
a firewall 11 that is affixed to the engine 3'. The air inlet duct
8' is essentially box-shaped and is in place between the exterior
surface 5 and the main gearbox 12.
[0036] In this exemplary embodiment the inflow flap 10' is
rotatably attached to the air inlet duct 8' by way of a hinge. When
the inlet filter element 9' and thus the air inlet duct 8 is
blocked, the inflow flap 10' opens as a result of the drive so
that, by way of a substitute, combustion air can reach the engine
3' by way of the further air inlet ducts 2' and 8'. This state of a
blockage or of increasing clogging of the cover filter 9' is then
detected by a pressure sensor 13 that is arranged on the air inlet
duct 8'.
[0037] The inlet-cover filter element 9' comprises a closed
attachment frame 14 that encloses a flat filter body 15. The filter
body comprises a protective grille 16 at least on the outside.
LIST OF REFERENCE CHARACTERS
[0038] 1 Cell [0039] 2 Air inlet [0040] 3 Engine [0041] 4 Air inlet
duct [0042] 5 Exterior surface [0043] 7 Central duct [0044] 8 Air
inlet duct [0045] 9 Inlet-cover filter element [0046] 10 Inflow
flap [0047] 11 Firewall [0048] 12 Main gearbox [0049] 13 Pressure
sensor [0050] 14 Attachment frame [0051] 15 Filter body [0052] 16
Protective grille
* * * * *